Due to the foreseeable depletion of conventional energy sources such as oil and coal, and due to the increasing greenhouse effect resulting from climate-damaging combustion products such as carbon dioxide, so-called renewable energy sources are becoming more and more important. These include solar collectors as well as photovoltaic solar modules. Solar collectors and photovoltaic solar modules generally have a very dark visual appearance. At the most in the case of crystalline silicon solar modules, the coloration is an irregular blue due to the silicon used. This limitation has so far resulted in considerable concessions when it comes to the installation of such solar modules. In Germany, for example, historic buildings having a red roofing tile surface may not be provided with solar modules under certain provisions. In view of these restrictions, there has been no lack of efforts to extend the areas of application of solar modules to not have to depend on the technically predefined color of these solar modules. However, this approach encounters the problem that a perfectly black solar module is regularly strived for in order to be able to efficiently absorb the sunlight and to achieve the best possible efficiency. Such black solar modules may be achieved, for example, using thin-film solar cells on the basis of CIS, CIGS and CIGSSe absorber materials. For the time being, colored solar modules may be obtained only by employing a lot of effort, i.e., indirectly. For example, colored glass is used as the outer glass pane of a solar module. These glass panes regularly rest on the solar modules as the outer protection layer against weathering. However, the coloring of such glasses is very weak in the reflected light. In addition, a high efficiency loss must usually be taken, since the majority of the incident light does not reach the light converting absorber layer of the solar module. Colored flat glass also involves a cost-intensive production. It has been tried as an alternative to insert a colored film between the outer protection glass layer and the light converting absorber layer. However, the color effect of such systems is similarly week as is the case when using a dyed glass plate. And again, considerable efficiency losses compared to conventional solar modules may be discovered. As another alternative, it was proposed to provide the outer protection glass with a colored screen printing. This method is also costly and results in significant efficiency losses. Furthermore, conventionally, e.g., in wristwatches whose face has a solar cell, a separate interference filter is applied to this solar cell to generate a color impression. This procedure involves at least one additional production step and also requires installation of additional material.
PCT Application No. WO 2009/042497 A2 describes an interferometric modulator (IMOD) for a microelectromechanical system (MEMS) which includes a protection, electrode and absorber layer as well as a so-called optical resonance layer and a reflector, seen from the side of light incidence. This resonance layer may, for example, be an air-containing hollow space or a layer made of a conductive or nonconductive material. By applying the optical resonance layer and the reflector layer beneath the light converting absorber layer, the efficiency is supposed to be increased even more. According to PCT Application No. WO 2009/085601 A2, the efficiency of the photovoltaic systems described in PCT Application No. WO 2009/042497 A2 may thus be improved even more by providing a plurality of dichromatic filters. Equipping solar cells or solar modules with an additional interference filter is described in Japanese Patent Application Nos. JP 2000 208 793 A, JP 09307132 A, JP 60148174 A, JP 2002 148 362 A, JP 601 425 76 A, JP 2001 217 444 A and JP 11 295725 A, for example.
European Patent No. EPb 468 475 A1 describes an amorphous oxide film which is essentially made of a zirconium- and silicon-containing oxide (ZrSizOy) in which Si/Zr atomic ratio z accounts for 0.05≦z<19 and O/Zr atomic ratio y accounts for 2.1≦y<40. With the aid of such an amorphous oxide film layer, a reflection-preventing coating for a glass which reflects thermal radiation is to be obtained, this coating having a good chemical resistance and mechanical abrasion resistance, and thus a good durability. According to German Patent Application No. DE 10 2004 005 050 A1, the energy conversion from radiation into electric current may be increased with the aid of color-selective interference filter mirrors which split up the solar radiation into different wavelength ranges and focus it photovoltaically on multiple semi-conductors optimized for different light colors. For this purpose, the sunlight is separated into at least two spectral wavelength ranges with the aid of flexibly situated interference mirror films.
Alternatively, it has at the most been possible until now to make use of the inherent color of the different module types. In this approach, however, the desired color regularly dictates the module system to be used. Thin-film solar cells on CdTe basis are associated with a black-green color impression, amorphous silicon solar cells on a glass substrate with a black-violet to reddish-brown color impression, amorphous triple silicon solar cells on metal substrates with an anthracite-blue-violet color impression, texturized monocrystalline solar cells with an anthracite color impression, monocrystalline silicon solar cells with a dark blue color impression, and multicrystalline solar cells with a royal blue color impression. The colors achievable using the conventional solar cells have so far typically derived from the absorber material characteristic to the particular solar cell type and may thus not be changed.
It would be desirable to be able to employ components, for example solar cells or solar modules, which have a colored appearance and which are accessible in a simple and reliable manner, without the need for completely replacing conventional production processes. An object of the present invention is thus to provide components such as solar cells or solar modules which provide a colored appearance having a uniform color shade throughout a surface of the component, e.g., of the solar cell or solar module, which may be set in a targeted manner. An object of the present invention is also to make accessible such colored components, for example solar cells or solar modules, which allow for the highest possible efficiency despite the colored appearance, i.e., the introduction of the color should reduce the module output only insignificantly, if at all. Another object of the present invention is to make available a method with the aid of which colored components such as colored solar cells or solar modules are producible on a large scale cost-effectively and reliably.